Variable voltage transformer



April 26, 1949. J. F. HYSLER 2,468,446

VARIABLE VOLTAGE TRANSFORMER Filed Dec. 13, 1944 2 Sheets-Sheet l i arra/wwsy April 26, 1949. HYSLER 2,468,446

VARIABLE VOLTAGE TRANS FORMER Filed Dec. 13, 1944 2 Sheets-Sheet 2 M array/v5) Patented Apr. 26, 1949 VARIABLE VOLTAGE TRANSFORMER John F. Hysier, Mount Vernon, N. Ward Leonard Electric Oompan of New "York Y., assiznor to a corporation ltppiication December 13, 1944, Serial No. 567,932

(61. I'll-119) o Claims. l Ll This invention relates transformers of the adjustable voltage type and ls particularly usein] where close soliustment of the output voltage is required or when it desirable to control this voltage over a wide range. The invention is $1 olicshle also to other variable contact devices. e main object is to provide an. improved form of apparatus which may he operated convenient- 2:; to secure any desired output voltage a, re zilhecl degree and over a wide range, such as from l voltage ohe lhaii voltage or even less than if according to the particular design. 25:; solosure described herein the voltage range vo age to about to per cent thereox". n-SE m. ostmeht is obtained providing c1 contact s? feces of 2s portion. he trons foo ohghgemem oy sliciaot. contest surfaces may he '1 successive turns e, 31 rtioh oi the do two he more turns between contacts to the vlhg the greater 2 J or he to the winding 1e case of "the usual steodown transformer to the secondary Willding in case of a, step-up transformer, This secures the oclvohtsge additional refinement of voltage ecliustment has the further advantage of conducting the smaller transformer current by adjustable contact engagement,

Another object to insure good one amiform contact of the engagin parts in all positions of control. Qther objects are the securing of proper insulation of the operating parts and the pro vision of a structure which is dependable and durable under long continued use. Other objects and advantages will he understood from the following description and accompanying drawings.

Fig. 1 is a side view of a preferred embodiment of the invention; Fig". 2 is an end view thereof; Fig. 3 is a. top plan view; Fig. 4 is a vertical sectlon on the line 4-4 of Fig. 1; and Fig. 5 is a. vertical section on the line 5I of Fig. 1.

The invention-is shown applied to the usual shell type of transformer although it may be applied to any other form. The laminae of the core III are shown clamped together by through bolts seeming; the most refined; eootrol, or

i On, one at each of the tour corners. The transformer windings encircle the central leg lb of the core. These windings are in three sections a transformer of the step-down type being shown. The primary winding is divided into two sections, on inner section [it wound close to the central of the core and an outer primary section lla wound on the outside of the intervening seconelary winding- 52, as shown Fig. 2. This brings the section Ma of the primary on the outside of the windings and thereby enables o, sliclahle con tact to engage successive turns of this outer sec-- tion for securing the refined adjustment of the output voltage. Also, by special relationship of the dliferent parts or the windings the leakage seduced permits the loser primary section l"! lacin Wound close to the central leg of the core owing to its small size of wire oompareol with the comparatively large size of wire of the secondary winding. 3 shows the leads We extending irom the secondary wimiinz to .ugs lih adapted for: oohnectloo to the cohsump on elrcmt A. leeoi We of the primary winding s shown in connection to-the supply circuit and extends he timer section ll of vthe primary end from which seotion e. lead lllri extenois to other section or" the primal", thereby connecting these two sections series with each other,

As shown in Figs and 3, the outer section of the primary shown in one continuous layer on the secondary winding. The upper lelt-hehcl portion of the outside section of the primary, as viewed in Fig. 2, is spaced trom and supported by a crosswise extending insulating strip l3 of imsulating material and of rectangular form. It is held in place at each ens; by being bolted. to a supporting bracket M of sheet metal. This bracket is shown formed in one piece having its central portion passing close to the top of the middle lee; of the core and within the transformer windings. At the sides of the windings the sheet metal is bent at right-angles to extend upwardly forming two trlangular-shapecl side portions as shown in Fig. 2. The front part of each of these side portions is again bent at right-angles to form outwardly extending flanges No, as shown in Fig. 3; and the insulating support 3 is bolted to the upper part of these outwardly extending flanges. These securing bolts also hold in place a spacing plate It at each end of the insulating supporting strip I: for holding the displaced portion of the outside winding in proper fixed position. As shown in Fig. 2, another insulating strip 18 extends crosswise within the outwardly spaced portion of the outer winding and is bolted in position at each end thereof to the flanges Na of the supporting bracket and below the insulating strip 13. The strip i8 is of less thickness than the supporting strip l3 so that the turns of the windin which pass over the strip it are bent inwardly, as shown in Fig. 2, to engage the surface of the strip it. Another strip 11 of insulating material extends crosswise in front of the strip 16 and is'held in place at each of its ends by the same bolts which secure the strip ii to the bracket it. The strip l1 serves to clamp the oi the outside winding firmly against the strip is and imposes a certain amount of tension on the turns where they pass over the strip [3. This insures that the outwardly spaced portions of the turns are. held firmly and permanently in fixed position. After the winding is completed and properly supported as already described, the insulation on that portion of the spaced turns which pass over the front of the insulating strip i3 is removed by grmding of! the insulation in order to expose the metal conductor of each turn over a straight path along the front of the condoctors. This enables a slidable contact 18 to successively engage the conductor of each turn of the outer section of the winding as it is moved crosswise along the path of the exposed contacts from one end turn of the winding to the other end turn.

The controlling apparatus is supported by a pair of sheet metal brackets located on the top of and extending along the sides of the transformer core. These brackets are angular and each have an upwardly extending portion I! at the outer portion of the core and an inwardly extending portion 19a and are secured in fixed position by the clamping bolts llla of the transformer core. The front end portions of the brackets is are cut away as indicated in Fig. 2 and thereby provide clearance space for the passage of the ends of a square metal conducting rod 20. The other ends 20a of this red are of reduced size to pass through and be supported by blocks 21 of insulating material which are secured on the outer faces of the brackets I! by the screws 21a. The insulated rod 20 has one of its ends 20a projecting beyond its support 2| and is threaded to receive nuts 20d for connecting thereto the lead wire llld from the source, the other lead Hlc from the source to the primary winding having already been described.

A screw shaft 22 is supported at its ends in bearings provided by the supporting metal plates 23. These plates are of general horseshoe form with the arms bridging and spaced from the rod 20, as shown in Fig. 2, and secured at their inner ends to the brackets I! by the screws 2Ia. One end of the drive shaft 22 is provided with a knob 220, although any other suitable meansmay be provided for turning this shaft or rod.

Mounted on the screw shaft 22 and adapted to travel thereon is a block 24 of insulating material. This block has a central circular opening, as shown in Fig. 4, through which the drive rod or shaft 22 freely passes. An opening is formed in the central front portion of the block affording space for a drive pin 25 which has a small projection at its inner end engaging the spiral groove of the threaded drive rod. The pin 25 is fixed at its front end to a central end portion of a yield- 4 able metal plate or leaf spring 26. The two side extensions of this spring are riveted, as indicated in Fig. 4, to the block 24. It is apparent that when the drive rod is turned, the engagement of the drive pin therewith will cause the block 24 to move along the drive rod in one direction or the other according to the direction in which the drive rod is turned, the leaf spring serving to hold the drive pin in engagement with the drive rod. It is desirable that this traveling block should not move beyond desirable limiting positions at each end of its movement, and to insure this limitation of movement, the outer thread portion of the drive rod is cut away at the desired limiting positions. These cut down portions of the thread are shown at 22a and 22b in Fig. 3 and provide beveled surfaces which extend circumferentially from-the inner diameter of the.

thread to the outer diameter. Thus when the block 24 reaches either of these positions, the drive pin instead of continuing to follow the groove of the drive shaft will ride up on the beveled portion 22b to the outer surface of-the drive shaft at that location and no matter how much the drive shaft is turned, the drive pin will continue to ride up on this beveled portion during each revolution of the drive rod and thereby avoid further travel of the rod beyond this limiting position. However, when the shaft is turned in the opposite direction, the drive pin will then follow the groove of the drive shaft and move away from its extreme position. Obviously these beveled surfaces 22a and 22b may be formed at any portions of the drive rod for limiting the travel as may be desired at the two end limits. The leaf spring 25 permits the drive pin to move outwardly and ride up the beveled surface to the outer portion of the drive rod at each limiting position and then forces the drive pin into engagement with the groove of the drive rod when it is turned in the opposite direction.

On the inner face of the block 24 is a rectangular projection 24a extendin longitudinally in the direction of the drive rod. Another block 21 of metal, such as brass, is secured to the inner face of the insulating block 24. The block 21 is shaped to embrace the conducting rod 20 and to also embrace the projection 24a of the insulating block, as shown in Fig. 4. The block 24 is provided at its upper and lower central portions with holes for permitting the insertion of screws 28, 28a and with openings of reduced diameter for the passage of the shanks of these screws to engage the block 21 and hold the same in fixed position to the block 24. Thus the block 21 is carried with the block 24 in its traveling movement and sufficient clearance is provided around the square conducting rod 20 to permit free movement along the same.

The upper central portion of the block 21 is provided with a cylindrical hole extendin from the inner face to near the front portion; and in this opening is a metal cylinder or plunger 20' having a slidable fit with the block 21 and serving as the contact holder. A spring 30 is located within the central opening of the holder 29 and impinges against the block 21, thereby biasing the holder 29 outwardly from the block. The contact I! previously described, is fixed to the projecting end of the holder 29 and engages the exposed contact surfaces of the windin along the path already referred to. A copper strip 2| is connected from the contact I! to the block 21, being secured to the latter by the screw bolt 28a. It is apparent that a good electrical connection is obtained to the conducting rod 20 and to the lead Ind from the contact l8 by its connection to the metal block 21 through the lead II and through the contact holder and by the slidable engagement of the block 21 with the conducting rod 20 in any adjusted position of the device.

The conductive enmgement of the block 21 with the rod 20 is increased by the additional means shown particularly in Fig. 5. This is accomplishd by a cylindrical pin 32 slidably movable through an opening in the block 21 opposite the top of the rod 20. This pin is positioned in an upper side portion of the block 21 as indicated by dotted lines in Fig. 1. A yieldable strip 33 of sheet metal forming a leaf spring extends over the top of the block 21 and is secured thereto at one end by the screws 34, the free end of the leaf spring engaging the top of the pin 32. The pin is centered in position in the spring by a small projection at the top thereof extending through a small hole in the leaf spring. It is evident that this device serves to draw the block 2! firmly against the underside of the conducting rod 20 for insuring good electrical engagement between the block 21 and the rod 20.

It is apparent that when the knob 22a of the drive shaft is turned, more or less of the turns of the outside section I la of the primary winding will be included in the supply circuit for obtaining a refined adjustment of the output transformer voltage. In one limiting position of the traveling block 24, all of the turns of the section Elia of the primary will be included in the supply circuit whereas in the other limiting position of the block none of the turns of the primary section i is will be included in the supply circuit. This improvement thereby not only obtains a refined adjustment of the output voltage but secures a wide range of control as determined by the number of turns in the different parts of the transformer windings. In some cases the winding having the variable number in sections as the particular embodirein described; and in such a case the lame portions of the outside winding the outer layer. The invention may he ed to either the primary or the secondary rmer windings or sections thereof and can, ectures oi the invention may be applied 'ransformer having a single winding and s outer layer and to inductive or reactive ings of various types. Also, certain feaiforlns of variable contact devices.

Although a particular embodiment of the invention has been described, it will be understood that various modifications may he made for adaptation to particular requirements without departing the scope of the inventitn.

Iclaim:

1. An inductive device comprising a core, a winding wound thereon having a plurality of layers, a support extending crosswise under portions of the outside layer of the winding for supporting such portions of the winding at a displaced position with reference to the remainder of the windingv said displaced portions having the insulation removed therefrom to form a contact path along adjoining turns, and a slidable contact movable along said path for successively engaging said adjoining turns.

2. An inductive device comprising a core, a.

- winding wound thereon having a plurality of Vince of the invention may applied to various layers, a support extending crosswise under portions of the outside layer of the winding for supporting such portions of the winding at a displaced position with reference to the remainder of the winding. 2. second support extending crosswise over said portions of the winding at one side of said first named support for holding the portions firmly against said first named support, said displaced portions having the insulation removed therefrom to form a contact path along adjoining turns, and a slidable contact movable along said path for successively engaging said adjoining turns.

3. An inductive device comprising a core, a winding wound thereon, said winding having exposed contact surfaces of certain of its turns positioned along a straight path, a contact movable along said path for successively engaging said contact surfaces, supporting means carried by said core, a screw shaft parallel to said path and journaled in said supporting means, a traveling block on said shaft for actuating said contact along said path, and a. yieldable pin carried.

by said block engaging the groove of said shaft, said shaft having a beveled surface extending from the groove of said shaft to the outer portion of said shaft for limiting the movement of said block in one direction causing said pin to pass out of said groove over said beveled sur-= face.

4. An inductive device comprising a core, a winding wound thereon, said winding having exposed contact surfaces of certain of its turns positioned along a straight path, a conducting metal rod extending in a direction parallel to said path, a metal block slidable on and embracing said rod, a contact carried by said metal block, a spring within said clock for hissing said contact outwardly therefrom for successively engaging said. contact surfaces along said path upon movement of said block along said rod, a spring-pressed pin carried by said leloclt and engaging said rod for exerting pressure of said hlocls. against said rod for insuring good electrical engagement between. said block and rod, and means for actuating said "clock along said rod.

A variable contact device comprising a series of exposed contacts along straight path, a conducting metal rod positioned parallel to said path, a metal block movable along and embracing said and in electrical contact therewith, a corn tact carried by said lalccl electrically connected therewith, a spring within said block for hiasing said contact outwardly therefrom for successively engaging said contacts upon movement or said block along said rod, a springqaressed pin carried by said block and engaging said rod for pressing said block against said rod for insuring electrical engagement hetween said Tclock and rod. and means for actuating said block along said rod.

6. An inductive device comprising a core, a winding wound thereon, said winding having ex posed contact surfaces cf certain of its turns positioned along a straight path, supporting means carried by said core, a conducting metal rod extending in a direction parallel to said path and. supported by and insulated from said supporting means, a metal block slidable on said rod, a contact carried by said metal block and biased outwardly therefrom for successively engaging said contact surfaces along said path upon movement of said block along said rod, a screw shaft parallel to said'rod and journaled in said supporting means, a traveling block of insulating material 7 on said shaft secured to said metal block. :nd 9, yieldabie pin carried by said insulating block engaging a groove of said shaft, said shalt having a, beveled surface extending from the groove 0! said shaft to the outer portion 0! said shaft for limiting the movement of said block in one direqtion by causing said pin to pass out of said groove over said beveled suriace.

JOHN F. HYSLER.

REFERENCES CITED The fc iiewing references are of record in the file of this patent:

Number Re. 19,957 777,118 954,518 1,043,272 1,225,227 1,288,018 ,2 7,822 1,561,204 1,947,328 2,163,644

Miner Dec. 2, 1941 

